There’s probably no diagnosis in the Emergency Department that confounds residents more than the practice variation between attendings regarding the evaluation for pulmonary embolism. Some folks send d-Dimers with reckless abandon on patients with near-zero pretest probability, others make emotional decisions to “take PE off the table” when faced with no other explanation, and then there’s a group that only very rarely pursues the diagnosis.
I rarely pursue the diagnosis – mostly because the epidemiological evidence suggests we’re only harming folks by making additional diagnoses of pulmonary embolism. Therefore, in a patient who is otherwise physiologically intact, a diagnosis of pulmonary embolism is more likely to result in iatrogenic bleeding risk rather than treatment benefit. And, then, there’s the backwards fashion in which I use d-Dimer: I order it at the same time as the CTA in an otherwise intermediate- or high-risk patient, and then cancel the CTA if the d-Dimer is normal.
I use this strategy based on this prospectively collected data from the Kaiser system, published obscurely in The Permanente Journal several years back. These authors evaluated 744 patients over 16 months who underwent CTA for rule-out PE, 347 of which had latex agglutination d-Dimer levels less than 1.0 µg/mL. In this cohort of 347, there were seven positive scans – six of which were ultimately found to be false positives. A handful of patients were lost, but the remainder had zero events in the three-month follow-up period.
So – d-Dimer negative, cancel the CTA, regardless of the pretest probability. So far, so good!
“Computed Tomography Angiography in Patients Evaluated for Acute Pulmonary Embolism with Low Serum D-dimer Levels: A Prospective Study”
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2911823/
This diagnosis and workup was one that frustrated me the most as an intern working in the ED. We'd get young healthy individuals with no risk factor getting a CTA.
Others made the argument that the attending physician ordering the tests was the ED favorite because of all of the billing!
There is essentially no incentive for Emergency Physicians to provide cost-effective care. Fewer tests, less revenue – higher potential liability? No thanks! The will soon come, however, when cost-conscious care is not simply the right thing to do….
Per other discussions, it's even worse that people with positive venous dopplers get CTA after the fact because it changes the DRG.
I can't do the "order at the same time" idea, because the CTA is markedly faster than the DDimer at my place.
Ah, well, it's not a literal "at the same time" – more a metaphorical "in my mind, I've ordered the CTA".